The problems solved by the present invention were discussed at length in the prior patent application cited above,and the background section of that application will therefore be repeated here.
Support pads are used in a wide variety of applications to provide cushioned support to an injured or otherwise sensitive bodily appendage. Such pads have the dual purpose of (1) providing orthopaedic support to the appendage and (2) protecting the appendage from further injury or damage resulting from contact with a foreign object or hard surface.
One common use of a support pad is as a cushioned foot sole in specialized footwear such as soft boots or patient walkers. These devices generally employ some type of soft, resilient material, such as foam, to provide cushioned support of a sensitive or damaged foot.
A particular problem arises when it becomes necessary to provide uneven support across the outer surface of an appendage. For example, an ulcerated appendage, often found in diabetic patients, requires pressure relief to the ulcerated area to allow healing. In this instance, it is desirable to have a pad which will apply cushioned support to the appendage, while refraining from supporting the afflicted area. For diabetic patients, the feet are commonly beset with such ulcerations, and it is therefore desirable to provide a cushioned support sole for a shoe or walker which is capable of providing specific zones of pressure relief.
Other approaches have addressed the problem of providing cushioned foot support. U.S. Pat. No. 2,598,217 (Bronson), issued May 27, 1952, discloses an invalid's boot with a thick insole. However, these approaches require replacement of the sole for each new patient, or for each new area of the original patient's foot which must be relieved.
U.S. Pat. No. 3,760,056 (Rudy), teaches a method for conforming a ski boot to the foot of the wearer by heating an inflatable bladder, distending it to the desired shape, and then cooling and deflating the bladder. The bladder can be subsequently be re-inflated to fit the wearer's foot. This method requires a mechanism for heating, which may be inconvenient or impractical when applied to a conformable sole. In the method disclosed, the inflatable bladder was placed over the foot to contact opposing sides, rather than underneath it as a support. Moreover, the elastomeric materials described in the Rudy patent typically may not provide the requisite comfort and cushioning generally required in a healing device.
A further method of providing support to an injured foot is disclosed in U.S. Pat. No. 5,078,128 (Grim, et al.) in which a removable leg walker includes a plurality of inflatable and adjustable bladder members in order to provide variable amounts of pressure to an affected limb as leg swelling increases or decreases. However, the bladder members of the Grim device do not retain their shape except as restrained by the surface of the appendage itself and thus do not provide the desired semi-permanent areas of relief to an injured appendage.
Incidentally, the above-cited U.S. patent application Ser. No. 07/965,750 discloses arrangements which provide relief using a pad of particulate material which is vacuum formed to the desired configuration.
From an overall standpoint, a principal object of the present invention is to provide a comfortable cushioned sole which may be conveniently modified to provide pressure relief to specific areas of the wearer's foot.
Another important object of the invention is to furnish a device which may be reused to provide relief to different areas of the patient's foot, or which may be used by other patients.
A further object is to provide a method for conforming a cushioned sole to the foot of a particular wearer, and of later reforming or returning the sole to its original shape.